Update defconfigs for g5, pseries and generic ppc64. Default choices
for everything, with the following exceptions:

 * Enable WINDFARM_PM112 on g5 and ppc64.
 * Increase CONFIG_NR_CPUS to 4 in g5_defconfig
 * CONFIG_TIGON3=y instead of =m in g5_defconfig
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>